Time War
by Bad Werewolf
Summary: Sequel to Arithmancy. You need to read Arithmancy to understand what happened to Donna. While Arithmancy was a Harry Potter crossover, there are no witches or wizards in this story. Rated T for mild language and because Captain Jack Harkness still exists.
1. Seatbelts

**Disclaimer:** I own none of it. Never have, never will. Although I would like anyone working for the BBC to interpret these stories as job applications for a writing position on Doctor Who.

Also during the full course of this story (for which this will be my only disclaimer) there will be, a Wayne's World quote. One ickle Stagate reference you'll not even see if you're not an avid fan of those shows. A blatant Terminator reference. One relatively obvious Hitch Hiker's Guide to the Galaxy quote. A small Star Trek reference. And an obvious Back to the Future reference.

Wow, I didn't actually plan to use all those, just added them in here as I spotted them in my proofreading. Spot them all, win a cookie (please note, no actual cookies may be reimbursed over Internet communications). Still, not mine.

**Summary: **Sequel to Arithmancy. You need to read Arithmancy to understand what happened to Donna. Although Arithmancy was a Harry Potter crossover, there are no witches or wizards in this story. Plenty of Time Lords, though.

**Author's Note: **I have never actually seen Gallifrey, or any episodes involving it in any way. Only thing I've seen for sure is the parts of the newer series that reference it. And its article on Wikipedia, which I am probably relying too heavily on.

And I know that it said somewhere official that it called the Rani a Time Lady once, and a lot of people have picked up on that and done this thing where Rose somehow becomes a 'Time Lady' - I just don't like the term, so I'm using the title Time Lord to mean both genders, it's been used in that way before, anyhow. I firmly believe the Time Lady thing was a mistake, and will continue to believe so until someone from the BBC offers me a job on their writing staff and in the interview says "oh, by the way, the Time Lady thing wasn't a mistake". So yeah.

I decided this story was best broken up into chapters, even though I actually wrote it in one piece, because it seems to be the only way to get enough reviews (hint hint). Now, if you've found this story and not Arithmancy or either of my other two stories in this series, go look at my author page. Seriously. I wrote this story fourth in the series (though as long as you read Arithmancy first, you can read the rest of these in any order, really).

**WARNING:** This story contains a _lot _of time travel, if you are not good at following time-paradox plot-lines, you may have some trouble following what's going on. It's a Time War, what did you expect, nothing but straight all-out fighting? Ha!

x x x

_"Time is our ally,  
Death is our friend,  
Where you world breaks,  
Our world will bend.  
What never was,  
And never will be,  
Is here and now,  
And we all shall see.  
That things that once were,  
And things that now are,  
Shall never have been,  
That is our power"_  
-Time Lord, by Bad Werewolf.

x x x

**Chapter 1: Seat-belts**

x x x

It was a bumpy ride, that's for sure. The TARDIS literally had to jump through hoops to get through the field that locked out temporal interference. During the journey they found themselves floating in mid-air three feet off the TARDIS floor, before being thrown towards one wall, just swerving in time to crash into the ceiling instead of the wall, before becoming weightless for another few seconds. This went on in a similar pattern for several minutes.

Finally they landed in an unceremonious heap. He was on top of her, and her knee was in a very uncomfortable place.

An alarm began to sound.

He groaned in pain, and rolled over to the side, allowing her to get up. She did so with one fluid motion and soon stood over him looking quite smug.

"Remind me to install seat-belts next time I try that." she said, her tone somehow taking on an effected aristocratic accent he had never heard her use before.

"If there is a next time." the Doctor grumbled, sitting up wearily, rubbing a bruise in the side of his head.

She shrugged innocently.

"What's with your accent?" he asked.

"What this? Stole it, sort of. Well you gave it to me. It was the Master's." she smiled, "Good, isn't it?" she added in her own natural accent, "Now you can tell when I'm channelling his bad attitude and when it's my own bad attitude you've got to worry about, space boy."

"Brilliant." the Doctor said sarcastcally, picking himself up off the ground and going to investigate the alarm, "And you can't really call me that anymore."

"Watch me." she leaned past him to look at the alarm, "Oh that sounds like the hull pressure alarm. I did re-route that, it really means we've broken through the temporal barrier, successfully."

"Uh huh." the Doctor said, examining the crossed wires to see she was probably right. He still didn't really believe it was possible, but at least there wasn't really a hull breach.

"You know where you're going here, now, right?" she asked, "Or do you want me to drive?"

"No!" the Doctor snapped quickly as she made to touch the control panel, "No no, I know where we're going. Don't need you throwing us all over the ship again. Really don't."

Donna grinned at him, and settled comfortably on the couch, which was conveniently placed on the far side of the room from where they had been thrown into walls, as if fate wanted to make them suffer for their insolence by denying them a soft landing.

"What did you intend to do once we got here, anyway?"

"It's about a decade before the Time War affected, if my calculations-" Donna started, but the Doctor interrupted her.

"Never say that! If you ever utter that sentence then your calculations will be way off." Earthlings call it Sod's Law, Time Lords had never really believed in it before the Doctor had gone and scientifically proved its existence.

"For you maybe. I have a better track record with calculations, if you remember." she said in her 'Master' voice.

The Doctor pulled an unamused face and began setting the very familiar course to Gallifrey. It had been so long, but he could never forget his way home.

x x x

"It's not here." the Doctor said flatly, pointing at the view screen and wondering what had gone wrong this time. They had arrived in the constellation of Kasterborous, and should now have been in orbit of Gallifrey. The Doctor knew they were in the right place, but where his homeworld should be there was only a sparse asteroid field circling around a binary pair of dying white dwarf stars incapable of sustaining life.

"Maybe the timelock only stopped it hitting the rest of the galaxy, but they kept jumping back anyway?" Donna suggested, her accent held not a hint of the Master in it, so he guessed it was the human part of her mind that had come up with it. It seemed like a perfectly reasonable assumption to make, too.

The real horror of the Time War had been that it had involved subversive attacks on planets' histories. In many cases the Time Lords would suddenly discover one of their greatest allies had never even evolved as far as bipedal let alone sentience, or one of their other enemies had been strengthened a thousandfold by a single Dalek at a key point in history.

The Time Lords had used the same tactic, too, and the Doctor knew damned well he had had the perfect opportunity to actually eliminate the Daleks at their creation but had been too soft to go through with it. Had he known then what he knew now, even with his current incarnation's aversion to the idea of genocide, he would have done it in a heartbeat.

"So how far back?" he asked her.

"Not very. Judging by the distance of the debris, the temperature of the stars and the distinct smell of asphalt, I'd say about six thousand years?" that was all the Master, he would have known without the accent.

"The smell, I wouldn't have thought of that, I would have said about four thousand." the Doctor said, starting to set the TARDIS to go back about seven thousand years.

"Temporpal-astrogational mathematics was never your top subject at the Academy, was it?"

"I preferred evolutionary temporal physics." the Doctor grumbled as the TARDIS started its journey back in time, remaining in the same physical location.

x x x

"That's the collision warning alarm." the Master's tone of voice informed him at its most evilly amused.

"I noticed." and at the Doctor's instruction the TARDIS hopped to a point directly behind the offending object. When he brought it up on scanners it turned out to be a Dalek warship.

"We could have been earlier." the Master informed, in the tone that wished they had. The Doctor was starting to think of it as three people in the ship instead of two, Donna's natural tone and the Master's were very different, even though he did realise it was only one mind with a bunch of extra memories.

Donna danced around to the other side of the control panel and hit the shields-up button before the Doctor had time to finish adjusting their course. Soon the warship had turned to face them and a barrage of laser beams rocked the ship, thankfully absorbed by the shield in spite of the inertially offensive side-effect, before the Doctor activated another time jump and they were out of there. Well, out of then. Back another thousand years.

x x x

"Not as bad as last time." Donna noted, leaning over the view screen to look at the golden-orange world they now orbited.

"Something's wrong, though." the Doctor noted, before pulling up a closer view of the planet. Its surface was completely barren, no atmosphere. No life.

"When do you reckon that happened?" she asked.

"It wasn't radiation, so there's no way to be sure."

"Keep hopping back a thousand at a time?" she suggested.

"Probably the best idea."

"Or we could go right to the big bang and hit the fast-forward button." she joked.

"I prefer the first idea, probably quicker." the Doctor said, silently wishing there was also a mute button.

x x x


	2. Warm Welcome

x x x

**Chapter 2: Warm Welcome**

x x x

"This is not the happy homecoming I anticipated when I came up with this plan." Donna noted in her 'Master' voice, "Are we there yet?" she griped. She had been laying on the couch, playing with a piece of technology she would never have dared touch as a human, now she had disassembled it and put it back together to do something completely different. She had turned Captain Jack's old sonic blaster into a portable mending ray for the medbay.

"Yes, we have life-signs." he said, examining the view screen, "And technology, too. The proper sort, not the primative rubbish back on Earth."

"Oi, watch it, space boy." Donna said, and he was happy to hear her tone was joking now, instead if genuinely offended.

"According to this readout, we've arrived only a few decades after the end of the Dark Time." he noted. It was sort of the Time Lord equivalent of the dark ages on Earth, except they had technology during the Dark Time, just no time travel.

"Wonderful." Donna said sarcastically, "Because I really wanted to know what _that_ was like."

The Doctor glared at her, then plotted a course to land in the Citadel of the Time Lords.

x x x

"Suspicion, paranoia, fear. Love it." the Master's tone said coolly, before Donna reverted to her normal accent, "You sure we're not back on Earth?" she asked in spite of the fact the sky was a rich burnt orange color and not the typical Earth blue.

"Positive." the Doctor said with a sulking tone.

They had been greeted upon their arrival at the citadel by armed guards. Five of them, with nice pointy staves the Doctor was fairly certain were capable of stunning with a touch. At least they weren't deadly weapons like Earthlings liked to use for this sort of occassion.

"Erm, Doctor..." she said, tapping his shoulder rather harshly and pointing down a path to one side. There stood a figure the Doctor and the Master had both read a great deal about, and only ever seen in holo-images.

The Doctor's eyes widened, and he muttered, "Timing is about right." in response to her.

"How should we do this? One for each, total reverence or..." what she did not finish with was total insolence. Approaching a great historical figure like this, especially one around whom so many wondrous legends circled, required some degree of tact, and/or planning.

"First option." the Doctor said, with a grin. The figure approached them and the Doctor bowed low. Donna stood there, eyeing this figure with some degree of contempt showing on her face. The histories were vague at best, they had no proof he was as great and good as legends said.

Rassilon, the founder of the Time Lords, looked at both of them carefully, "Identify yourselves."

"Donna Noble." Donna said with all the politeness she generally reserved for bureaucratic officials, that is to say fault could not be picked in her manners but it was quite obviously only a front.

The Doctor blinked a few times, and muttered something under his breath, but no one else heard him.

"Your name." Rassilon ordered.

"I think he said 'we're not worthy, we're not worthy'." Donna joked. Five guards and one all-powerful ruler glared at her. The Doctor fought the urge to laugh, which wasn't an easy task.

"My name is-" the Doctor began slowly, reluctantly, but just at that moment there was an explosion in the sky overheard.

"Lovely timing." Donna muttered. She had been curious about the Doctor's real name for some time, and it had irked her that the Master did not know it.

"Quickly, then." Rassilon said briskly, "How is it that you have in your possession an experimental machine for which I have yet to perfect the design?"

"Well what is it supposed to do?" Donna asked in her most imperious voice. _'So help me'_, she thought, _'If he says anything but time travel I'll have no choice but to laugh in his face'._

"Time travel." Rassilon whispered, "You come from the future."

"About four hundred thousand years." Donna said, glancing at the Doctor for confirmation. He nodded. Four hundred thousand years worth of Gallifreyan history screwed up by those metallic bastards, they would pay.

Another explosion rang out, and the three Time Lords and five Gallifreyan guards all looked up into the sky.

Donna swore in Gallifreyan, happily choosing to forget that the TARDIS translated it so the two born Time Lords heard only English and Rassilon probably did not understand the words she used. The English translation sounded something like 'being who is one's own father', although Time Lords did actually have a single word for that in the time the Doctor and the Master came from. The Doctor scowled at her, clearly knowing what she said.

Debris from the intercepted Dalek ship fell down over them, and Donna held up her hand to stop one particularly large piece from landing on her head. It was instinctive and she had never even considered before now the vague knowledge in the back of her mind that Time Lords could manipulate the actual fabric of time around them. The piece of debris had frozen in mid-air about a foot above her, by her will alone. She stepped aside and let the large chunk of metal fall where she had been standing a moment ago.

Rassilon seemed stunned by this act, and was probably contemplating how great his people had become somewhere behind that shocked expression.

The Doctor touched the twisted metal cautiously, it was apparently still hot because he pulled his hand back quickly, "Vardus four." he muttered, "About twenty years ago."

"Are you suggesting sabotage?" Donna asked, all innocent tones.

"What else?"

x x x

A pair of very tenacious- and even by their race's standards, genius- Time Lords was just what this war needed to turn things around. The Daleks' efforts to tame and control the Racnoss, increase the strength of the Great Vampires, introduce Cybermen to an earlier point in time, redirect the Minyans self-destructive behaviour towards the Time Lords, wipe out the Lanteans and Alterans twelve centuries before their technological peak, and most importantly the unceremonious attempts to infiltrate and blow up Gallifrey more than fifty times, were all meticulously and systematically thwarted.

The history of the Dalek race was now so convoluted that finding the original point of creation for the species was no longer an option. Instead they spent about five hundred years, from their own perspectives, jumping back and forth and undoing the damage the Daleks caused to the time-lines, usually involving hunting down a single Dalek and eliminating it before it could achieve its goal.

Donna had jokingly made reference to a certain TV series she had once watched re-runs of, called Quantum Leap. "Putting right what once went wrong, and all that." she had said.

It was a fairly accurate analogy.

Eventually, they had blown up about seventeen hundred and sixty-three Dalek mother-ships (or was it seventeen hundred and sixty-eight? Some where debatable, especially the couple of times they'd blown up one ship, then gone back in time and blown it up again before the first time they blew it up). Eliminated nine hundred and six individual Dalek infiltrators. Wiped out an entire Cybermen invasion, then gone back and prevented said invasion from happening in the first place. Helped Rassilon, the forefather of Time Lord technology, to defeat the Great Vampires in what had previously been known as the Second Time War. Decided Rassilon himself was- in Donna's own words- a 'jerkwad', and not all history made him out to be. Then went back and stopped all Dalek interference in the First Time War as well.

x x x

Donna yawned in a rather bored fashion. They had gotten up to about three hundred years before the Doctor and the Master had been born, and were now once again thwarting an attempt to blow up Gallifrey. "It's getting repetitive." Donna noted.

"They don't know that." The Doctor said with a brief grin, before going back to disarming the now familiar explosive device. They always used the same thing, as if they really did not realise the Doctor and Donna had been doing this for the last five hundred years. This must always seem to the Daleks like the first time they came up with the idea. Probably because it was.

She glanced at her watch, then looked up, "Three minutes, maybe?"

"Give them four, it gets longer every time." the Doctor said dismissively. True. It seemed like the further back in time they had been, the more prepared for the intervention the Daleks had become. They were working in opposite directions in time. The Daleks kept jumping further back each time, the Doctor and Donna had gone to the earliest point in time that was affected and started working forwards.

Soon enough, the explosive was disarmed and the Daleks swooped in through the ceiling. "That was four and a half minutes." Donna noted, "And there's only three of them this time." she sounded truly gleeful at that fact. Last time there had been twice as many.

"Exterminate! Exterminate!"

"Exterminate this." Donna said brightly, before cheerfully twisting time around the Daleks with a slight wave of her hand, so that they continued to swoop down while their laser beams did not, releasing her grip on time at just the right moment to allow the laser beams to hit the three Daleks in the back of their domed little heads. She wondered to herself why the Doctor did not use that cheat more often when he got into fights. Then she realised, that was exactly why, because it was a cheat. _'Terminally honest, that one,'_ the Master part of her mind thought.

"I wonder if we could teach a Cyberman to say 'hasta la vista, baby' and sic it on some Daleks?" she joked, looking at the charred remains with some degree of pride.

"I'd rather not try." the Doctor said in a deadpan tone, fully aware that she had been joking.

x x x


	3. Paradoxes Are Fun

x x x

**Chapter 3: Paradoxes Are Fun**

x x x

Finally back to about their own lifetime, from the Gallifreyan perspective anyway, "About damned time." Donna grumbled, "Only five hundred and three years, not a bad run without a single death or regeneration."

"Tempt fate, why don't you?" the Doctor muttered.

Donna simply grinned infuriatingly, and led the way out into the Citadel. Time had been kind to this place and it looked very much as it had done in Rassilon's era, although that was mostly because the Eye of Harmony allowed it to become truly timeless in that literal sense where it actually does not age.

Donna wandered down the clean hallways, which while they were theoretically white had a golden tinge from the filtering of light through the orange sky.

The Doctor really did try to look like he was leading the way, but failed quite miserably as Donna knew as well as he did exactly where to go. It did not take long before they found themselves in the high council chamber, where important matters were usually decided.

"I think I'm already here." the Doctor noted.

Donna's eyes were drawn to the man standing off to one side, staring at them like he'd seen a ghost. He was shorter than the Doctor standing next to Donna, his hair was longer and kind of wavy but the same shade of brown. His eyes were grey, not the brown she was used to, and he looked distinctly younger than his tenth incarnation, though Donna rightly guessed that was more due to the five hundred years fighting in the Time War which had made her Doctor look like, if he was human she'd have guessed in his mid-to-late forties (funnily enough, she had failed to age yet, perhaps the Doctor had been running around for a few centuries in-between times before she had taken on the Master's memories). Still, she could tell with only the slightest glance that this younger man was also the Doctor. Something about the way time itself rippled around him, a unique aura she could perceive, though she was certain she would never had seen it had she still been human.

"Which one?"

"Eighth, I think." her Doctor muttered.

"You!" the younger Doctor snapped, pointing at Donna, clearly recognising the Master's presence and probably very confused by this as, at this point in their shared history the Master had already used up all thirteen lives and was supposed to actually stay dead. "How?" he asked, his tone turning from anger to horror as he tried to think of a way it was possible and came up blank. He apparently did not know that the Time Lord council had already resurrected the Master, who had then promptly chickened off to the end of the universe about three days ago (Gallifreyan relative time).

Her accent took on the Master's tone as she grinned at him and said, "Not what it looks like, I assure you."

Her Doctor spared the briefest glance for the council, then decided to deal with himself first, make sure he didn't do anything stupid. He walked over to his younger incarnation and started talking very fast, in a low voice, finally finishing his sentence audibly, "So you see she's mostly harmless."

"Unless you're a Dalek, I've harmed a lot of those recently." she noted cheerfully, examining her fingernails as if this conversation didn't really warrant her full attention.

"Funny thing is, I don't remember talking to myself when I was here last time." her Doctor noted.

"Time-locked, your memory and past isn't affected by what we're doing here now, until we start to change the final result." Donna answered.

The sound of someone clearing their throat for attention caused them all to look up at the leader of the council, "Fascinating though I am sure this reunion is, we have a more pressing issue to deal with."

"If memory serves, this is the big day." the Doctor said. His eighth incarnation frowned, folding his arms defensively.

"I assume you have a plan." the younger Doctor asked.

"Always." Donna replied with a grin.

Her Doctor nodded in agreement, "Wouldn't have come to a party like this without one."

"Citadel shields breached, intruder alert." a soothing yet still electronic voice informed them over the internal communication system. Why such a calm tone was applied to intruder alerts, Donna could not fathom.

The Daleks themselves were temporally resistant, that is to say; time-bending abilities could not affect or penetrate their metal shells. Donna had figured her way around that quickly and easily, and now put it to good use, using the technique she had happily dubbed 'friendly fire' to make them shoot themselves as five of them attempted to breach the citadel.

This time even the Doctor- both Doctors- took her cue and used her cheat to defend themselves.

Overhead, the mothership coordinating the invasion suddenly found itself surrounded by twelve TARDIS ships, all of which had chosen a form strongly reminiscent, in Donna's mind at least, of a Romulan warbird straight out of Star Trek... except these were silvery-blue in color.

Unfortunately for these TARDISes, the Daleks seemed to have anticipated such a move, and succeeded in shooting them all down, except for one, which managed to vanish just in time, only to reappear as the perfectly plain silver block of metal that was their default appearance, right in the middle of the council chamber.

A woman literally fell out of it, apparently stumbling over her own feet, her hair was short and blond and she had an authoritative air about her. Something in Donna's mind recognised her, but could not place her clearly. "They were expecting us." the woman said, as if trying to explain her failure to shoot down the Dalek ship.

"They travelled back to this point to eliminate us before we attack them." the tenth incarnation of the Doctor said, glancing at Donna, a silent communication, he wanted them to split up, for her to keep an eye on his younger self. She knew without the words even needing to be thought let alone said.

"Our non-interference laws-" the council leader began, but Donna interrupted.

"So you don't want us to interfere with their interference with our own history, is that it?" it was her own accent, not the Master's.

Without even looking up she held up her hand, and a laser bolt that had been aimed for the back of her head froze in midair. "That's just rude." the Master's tone said coldly, before she turned around and pressed the metaphysical rewind button, returning the laser bolt to its sender.

"I remember that..." the tenth Doctor murmured. The time-line must be changing drastically for him to recall something that happened after the time-lock from his perspective.

"How else would I have known to do it, you showed me." Donna said, grinning.

"Gotta love self-fulfilling time-loops." the blond woman said, making a deliberate effort to stand up straight, before taking the older Doctor's hand and leading him into her TARDIS.

"This way." Donna said, leading the younger Doctor back to her own Doctor's TARDIS out in the hallway, "You never allowed me to fix the chameleon circuit. I tried, you know." she told him as they prepared for takeoff.

He laughed at that, but then asked the important question, "Where are we going?"

Her voice was cheerful, as if they were playing a game and she was enjoying it, when she answered him, "The Dalek mothership. Where else would we go if we want to explode some Daleks?"

x x x


	4. Rewind

**Author's Note:** The song played here was, like the one I used at the end of Arithmancy, in the charts when I wrote this. As for the others, two were actually played by the Master during his reign as Harold Saxon, and one was played on the Doctor Who confidential about the latest Christmas episode. Viva La Vida actually did give me some inspiration to continue writing this story, before that confidential episode, though. And you can blame Meatloaf not coming to Belfast during his last tour for his song getting onto the Doctor's banned list.

x x x

**Chapter 4: Rewind**

x x x

The older Doctor helped his blond friend start up the time-shift, grinning all the time, "Long time no see, Romana." Contrary to the opinion of certain other Time Lords he could name, the Doctor had never been attracted to Romana, and instead considered her to be like a younger sister. A younger, very annoying at times, much better academically (the Doctor actually was very smart, but he had been bored senseless at the Academy and a deliberate underachiever, Romana liked to rub it in that she got better grades than him), sister... but still.

"I saw you half an hour ago."

"That was two lifetimes."

"One for me."

"Ouch." the Doctor muttered, realising this meant she had actually regenerated within the last half hour. No wonder her balance was off, changing your whole body did tend to affect your equilibrium somewhat. "What happened to your crew?"

"The Daleks have a new toy." she said coldly, "It prevents regeneration. I was lucky, they failed to find me where I'd died." she said, frowning at thin air about a foot above the control panel she was supposed to be reading. The Doctor flinched at that thought, "So what's your plan?" she asked him.

x x x

Donna flipped a series of switches around the console and said, "Twenty-first century Earth. Surprise me."

Before the Doctor could express his confusion at this statement, music began to play. A fast beat and a female singer, the Doctor had not, in this incarnation, heard the song before. Then again, he was still mentally stuck in the twentieth century when it came to Earth.

The song was actually called 'Hot and Cold', as sung by Katy Perry.

During his time as Harold Saxon, the Master had developed quite a taste for popular Earth music, and Donna had never really been averse to it either. The Doctor had officially banned the songs 'Voodoo Child' and 'I Can't Decide' from ever being played in his TARDIS, and after their first decade together he added 'Viva La Vida' to the list, too. He had also made some pretty dire threats after the time she had played the last verse of 'Paradise By The Dashboard Lights' on a continuous loop for three and a half hours straight, but anything else was fair game.

Now, in practiced moves developed over the centuries, Donna began flipping switches and turning dials on the console to the beat of the music. It was a talent she had developed mostly from the Master's memories, the drums, the music, her heartbeats, all in synch. Before the music had got past its introduction they were through the Vortex and had landed somewhere the Doctor wouldn't be able to discern. Yet.

As the music kicked in to the chorus she turned and threw an object at the Doctor, who was still standing by the door of the TARDIS a bit dumbstruck. He caught it and realised it was a small explosive device, not armed yet, but it would make Earth's best weapons of mass destruction look pathetic in comparison once it was set off.

The doors opened behind him, and he saw they were in the engine room of one of the Dalek ships. The next course of action was perfectly logical. Throw explosive, and leave before it goes off. He threw it, and the door closed. Donna had set a new course, but certain failsafe devices had been pulled out of the top of the console and disconnected, the wires sitting out to show where the circuits had been.

x x x

Meanwhile, the older Doctor and Romana, in her TARDIS, had begun something similar. He had rewired her ship for the same function.

As both TARDISes disappeared from their respective Dalek ships, two huge explosions set off, and the two ships were destroyed in a rather spectacular pyrotechnic display. But it was a vast fleet and many ships remained.

x x x

"What did you do?" the younger Doctor asked, during a convenient instrumental lull in the music, as Donna turned two dials at once counter-clockwise, then set the ship to rematerialise.

"We're going to be in a few dozen places at once." she answered throwing another explosive device to him, and the doors opened onto another Dalek ship's engine room.

x x x

Four ships exploded at the same time.

Rewind.

Six Dalek ships blew up at once.

Rewind.

Eight ships go boom.

Rewind.

x x x

They were still on the same song, having successfully gone through the same fifty-five seconds four times, when the Daleks finally caught on to the exponentially increasing temporal disturbance they were generating with this exercise.

The ship Donna had been aiming for managed to make itself elsewhere when they materialised.

"Someone call the Doctor..." the words played through the speakers, and Donna personally blamed that line of the song for the entire problem. The Doctor _had_ gone and made himself a focal point for Sod's Law during an experiment while he'd been at the Academy. It made perfect sense to her that this was almost entirely his fault, and that the song was somehow also to blame.

A laser blast rocked the TARDIS and sent it spiralling down towards the planet as the music continued a bit too cheerfully "Stuck on a roller-coaster, can't get off this ride." Donna decided she would add this song to the banned-list herself, if they survived. Not because it wasn't a good song, just because it would forever be associated with event this in her mind.

As they fell out of control, the Doctor stumbled into the couch, catching his foot on the control console as he fell. His right ankle now bent the wrong way. Without missing a beat- somewhere in the back of her mind she wondered if it was the music or the adrenalin- Donna grabbed the healing ray she had converted all those years ago from Jack's sonic blaster, which had never actually made it to the medbay after all, and tossed it over to where the Doctor had landed.

She only just managed to keep a good enough balance and grip on the console to try to stabilize the ship for re-entry into the atmosphere, which had now become unavoidable.

x x x


	5. Death Is Just A Minor Inconvenience

**Author's Note:** I apologise for my absence this last week or so. Long story short (one word, even!): transplant. I'm better now, but I've been told I can't have asprin anymore, it'd kill my new kidney. I'm not even joking (for those of you nerds enough to know why that's funny in the first place).

x x x

**Chapter 5: Death Is Just A Minor Inconvenience**

x x x

The TARDIS fell from the sky, landing on its side, a smoking hole on its roof and sparks flying from beneath it as it skidded to a halt just outside the entrance to the chamber which held the Eye of Harmony. Not bad aim considering the manner of their descent. Donna kicked the door open and dragged an injured and limping Doctor out of the TARDIS. At least he could walk at all now, the healing ray had made that much possible.

The sleek silver block that was Romana's TARDIS appeared next to them, and Romana and the elder Doctor leapt out. Seeing each other alive and well, Donna and her Doctor hugged briefly, although he did demand, "What did you do to my ship?!" before being rudely interrupted by the screeching from overhead.

"Exterminate! Exterminate!"

Another blast from above struck Romana's TARDIS, leaving a blackened dent in the side. "Run." both Doctors shouted, almost perfectly synchronised. And so they ran.

The Chamber beneath the Citadel was huge, and had only been rediscovered by the Doctor and Master a few centuries ago, several lifetimes ago. It had been the Time Lords' own Chamber of Secrets, so to speak. Within was the Eye of Harmony, the source of all the Time Lords' power, the nucleus of a black hole which acted as a gateway of sorts to the time vortex. Visually, it resembled a very small sun, suspended within containment fields that drew their power from the Eye itself. Theoretically, it was impossible to break through these fields without the Key of Rassilon. Theoretically. Luckily, they would not have to test this theory, as Romana actually knew how to get the Key.

Lesser such gateways existed within their TARDISes, giving a TARDIS the ability to traverse the vortex through time and space. It had long been the Time Lords' final fail-safe, to prevent the Eye from falling into enemy hands they must destroy it. The resulting temporal distortion would destroy Gallifrey in the process, and weaken any TARDIS that survived the destruction, but it would also trap their enemy within this time-line, they would not be able to harm the rest of the universe.

Romana and the younger Doctor ran on to the controls that would manipulate the Eye, while Donna and her Doctor turned to face their attackers, to hold them off. Buy some time for the other two to activate their last resort. Donna's favourite 'friendly fire' technique could only do so much, and the Doctor began to manipulate a shield generator with his sonic screwdriver. Just a few seconds and he'd buy them at least five more minutes.

He concentrated on this, and barely heard when Donna shouted, "Doctor!"

He did, however, notice the laser bolt that stopped right in front of his nose. He looked up to see Donna holding her hand out to him, holding the projectile in place by freezing it in time.

He sidestepped to allow it to pass him, but not fast enough. Before she could release her hold on it, another blast struck her from behind. She fell, and the first beam hit the wall just a millimeter from the side of the Doctor's head, he could smell where it had actually singed his hair. In spite of himself, he could not help thinking that she _had_ tempted fate, it wasn't so much surprising as it was horrifying.

A Dalek with an unfamiliar device on its arm now landed and approached Donna. Though he had never seen such a device before, the silver-black energy shimmering around it, most likely invisible to humans (although he was in no position to test that theory right now), clearly told the Doctor what it was. It was the 'new toy' Romana had told him of, it would prevent a Time Lord from regenerating.

Before he could react, to try to defend her, a flash of golden light shot out from the Eye of Harmony itself, visually reminiscent of a solar flare, striking Donna's prone form before the Dalek could reach her. In an instant she rose into the air, coming to her feet with the blaze of golden energy that signalled a regeneration.

Her hair darkened but remained red. Her face changed very little but just enough for it to be noticeable, almost as if she was consciously trying to stay as close to her original appearance as she could. She grew half an inch taller, he thought, but that could just be the aura of power around her as only the tips of her toes were actually touching the ground.

The golden light did not entirely fade, and when she opened her eyes they glowed with that same light. She spoke with a dual toned voice as if two people were speaking in perfect synch. Donna's own voice and another, incredibly familiar to him, but in the heat of the battle he could not place it.

"Open the Eye." Open it, not destroy it.

And with those words the light dissipated. The Doctor found himself staring into green eyes, where they had once been hazel.

"You gonna lock the door?" Donna said in her own, barely changed voice, with a hint of her 'Master' accent, and the Doctor snapped out of it just in time to make the final tweak that activated those pesky shields, keeping the Daleks out. For now, at least.

x x x

Luckily from one perspective, unluckily from another, Romana and the younger Doctor had only just managed to unlock the complex temporal safe which contained the Key of Rassilon, the only means of accessing the Eye of Harmony. Donna reflected on the fact they really liked big pompous names for things, but decided she would comment at a later date. It was lucky in that they had yet to begin the self-destruct process, but unlucky in that they were running out of time and still had a lot to do to open the Eye as the elder Doctor commanded them when he reached them.

After staring blankly at him for a moment, Romana asked, "How could that help us?"

"No time." Donna snapped, glancing warily at the force-field that was holding the Daleks back for now. Without warning, and probably to their great displeasure, the Doctor reached out to their minds with his. Donna made no effort to resist him, Romana frowned, but also did not fight. The younger Doctor resisted on principal.

As a highly advanced subset of an ancient race, gifted with telepathic ability, Time Lords were able to perform what they refer to as a Blending. Where two or more minds come together to think as one. It's frowned upon by the Time Lord High Council, and not advised unless you fully trust the other participant(s) with your life and soul, because in this state there is no way to know who is in control, who is thinking what, they become literally one mind.

Often used by TARDIS crews to help coordinate through precarious or complex manoeuvres, and occasionally used by married couples for reasons Captain Jack would love to hear about in great detail, it is generally assumed that if any illegal act is carried out by a Time Lord under the influence of a telepathic Blending, all participants of the Blending are guilty.

They had already broken Time Lord laws just by being in here, so they had little to lose in that sense.

It took Donna telepathically opening her mind to the younger Doctor in a submissive form, to prove she was not really the same person as the Master, before he would allow his elder self to complete the Blending. This hesitation only took half a second, and then all four of them began to work as one, manipulating different parts of the controls to the Eye of Harmony in perfect time.

They were doing something that had never been done before. The Eye of Harmony had a containment unit and thirteen fail-safes for a reason. It was a black hole. It could destroy the planet if opened incorrectly. Then again, the original plan of destroying the Eye would have had an absolute certainty of destroying the planet with it. This plan actually had a chance of success, though it did rely on precision and skill. Between the four of them, however, it was still taking far too long.

Their five minutes of borrowed time was up, and while none of them could tell who was in control of the telepathic Blending, or even whose hands were whose anymore, they did know who broke the link.

In a moment of panic, Romana shouted, "It's too late, we'll never finish this in time!" The other three looked up to see that the shield had been broken and Daleks were swooping into the chamber preparing to attack.

"Oh yes we will." the younger Doctor said, and before they could stop him he had taken the last two circuits that needed to be connected to open the Eye, from opposite sides of the control console, one in each hand, and the energy coursed through his body, burning him up from the inside. It was fatal and they had all known such an action would be, which was the reason they had been trying to work around the console instead of resorting to such drastic measures. Only his older self had failed to even try to stop him.

But now the Eye of Harmony was open, lighting up the chamber with a brilliant brightness not even Gallifrey's own twin suns could have managed. The power within was unleashed upon the invading Daleks, and when Donna was the first to look up, she was unable to resist the sardonic mutter of, "Expecto Patronum, Doctor."

The Doctor looked up from the fallen body of his younger self to see the glorious golden energy they had unleashed had taken on a physical form, which charged down the Daleks and disintegrated them with a touch, leaving everything else unharmed around it. A huge golden wolf made out of pure energy from the Eye itself.

With a victorious howl and a fleeting glance at the Doctor, the words "Three for three." echoed in their minds and the wolf dispersed. A shock-wave, a pulse of energy, erupted from it, spreading at approximately the speed of sound, disintegrating every Dalek in its path. The three Time Lords watched this wave through senses humans cannot even dream of let alone comprehend, as it accelerated exponentially, and traversed the entire galaxy, then onwards through the whole of existence. Some Daleks might have escaped through time travel, if they were quick enough, but there was no escape through space, and the aftershock of the wave would break any time travel devices that slipped through it, trapping any survivors in the time they fled to.

Only when it was all over did they turn their attention back to the fallen body of the younger Doctor. He remained distinctly dead. The still living Doctor muttered something about a fictional character named Marty McFly, and Donna bit back her instinct to laugh in respect for the seriousness of the situation. With all of time and space from which he could have found a much more sophisticated comparison for the danger he was in, and he referenced an Earth movie. Typical.

Not that she was innocent on that count, but she had been born on Earth, what was his excuse?

x x x


	6. Where Do We Go From Here?

**Author's Note:**Due to very prompt reviews (which makes me very happy), and by way of an apology for my prolonged absence, here's the last chapter up the very next day, no waiting. And yes, there will be a continuation of this, I've even got a plot involving the reason behind the Drums! But it's WIP at the moment, so will take a little while.

In the meantime, watch out for my next fully-fledged crossover coming soon: **_The Bad Wolf And You_**, where we see Daleks invading the Earth, find the Master's TARDIS and another supposedly-lost powerful magical artifact, and Ron Weasley says the blatantly obvious at just the right time for it to save the world.

x x x

**Epilogue: Where Do We Go From Here?**

x x x

It was late at night in the Torchwood hub. The tattered remains of his team- Ianto and Gwen were all that had survived- were at home, most probably fast asleep.

Captain Jack Harkness was in the main room of the hub, sitting at a desk across from his favourite nemesis, Captain John Hart. They were passing the time by arm-wrestling, of all innocent things. Neither was likely to win anytime soon, until a beeping distracted them.

Jack lost his concentration first, and his arm slammed into the desk leaving a nasty red mark on his knuckles. As he rubbed his hand irritably, John checked his wrist device, which was the source of the beeping. "Another one!" he exclaimed, surprised.

It had only been about five minutes ago, from their perspective, that they had returned from their last little adventure involving the Doctor, the Master and nowhere near enough indecent activity. In fact, there had been none at all, which had really made the whole event quite boring.

Jack leaned over the desk, grabbing John's arm so as to look at the device properly, "Holy- ...wow... damn, I'm impressed." he said, gaping at the location of the vergence they had detected. That whole area of space hadn't existed last time he'd looked, but he'd read the legends and heard the Doctor talk about it enough to know where it was. "Oh but we are definitely not going there." he added definitively.

"Why not?" John asked, with a confused frown. On anyone else that expression might have been called a pout, but not on him.

"No humans allowed." Jack said shrugging cheerfully.

He knew without a shadow of a doubt that he'd be hearing about this before long. The Doctor would be far too pleased with himself not to share, and he could already guess the Master's opinion on the matter too. He wondered which one came up with the plan, but was certain he'd hear more than he wanted to about it soon enough.

"Rematch. Now." Jack ordered.

x x x

It had been an hour since the younger Doctor had sacrificed his life to save his world. His elder self was still in existence, therefore it was perfectly reasonable to assume a regeneration would happen any moment now, but Donna was beginning to get impatient. They currently sat around the control console of the undamaged and younger version of the Doctor's TARDIS, the Doctor's body lay on the couch, and none of them had spoken yet. They were putting off thinking about the elder TARDIS until the Doctor was restored, she could heal herself, and this was a bit more life-threatening.

Donna glanced at her watch again, and poked the elder Doctor in the arm as if to check for transparency, as per his comparison to a certain movie earlier.

The Doctor glared at her, in so much as to say _'I'm still here, now just quit it!_'

Just as they were distracted from their vigil, almost as if he was waiting for his audience to stop staring, the younger Doctor's body began to glow with the golden light that signalled a regeneration.

Romana looked away out of habit, but Donna, who had never witnessed another's regeneration (not a proper one, anyway), and the Doctor who was a bit too morbidly fascinated with it all, continued to stare. Both became temporarily blinded as the glowing light around the younger Doctor's body intensified. When they could see again, he was breathing, but he was almost unrecognisable.

His hair was shorter, darker, his face was sharper and more angular. The first thing anyone could find to say was spoken by the elder incarnation of the Doctor, "Did my ears really look like that?" he demanded, staring at himself.

Several more hours passed, during which Romana stayed with the newly regenerated Doctor, and the other two worked on repairing their TARDIS. The Time Lord High Council had been wiped out by the Dalek invasion, and Romana would remain to try to restore order. The younger Doctor would be sent away from Gallifrey. Even Donna, with the Master's full knowledge of time itself, couldn't quite figure out how the two time-lines now fit together. Still, what's done is done, and they _had_ just saved their world.

"Hey, Doctor?" Donna asked, to get his attention, as they stood in the now fully repaired TARDIS, thinking about where to go next.

"Hmm?" he replied.

"Correct me if I'm wrong, but isn't the Eye of Harmony supposed to facilitate inter-dimensional travel."

The Doctor blinked a few times, clearly having to think about this statement. Then he very slowly nodded.

She grinned at him for a moment, before asking, "Well then, don't we owe someone a thank you? In person?"

x x x

The End.


End file.
